Desert Southwest Expansion Project

Introduction

On April 3, 2026, FERC staff approved Transwestern Pipeline Company, LLC (Transwestern) request to enter into FERC’s Pre-filing Environmental Review Process (Pre-filing Process) for the planned Desert Southwest Expansion Project. More information may be found in FERC Docket No PF26-9-000 in FERC's eLibrary. Please note that the project has not been approved at this time.

Desert Southwest Expansion Project Route and Facilities

The Desert Southwest Expansion Project is an expansion of Energy Transfer’s Transwestern Pipeline.

The Project consists of a new approximately 520-mile-long 48-inch-diameter pipeline interconnecting with Transwestern’s existing system; 15 new receipt and delivery laterals and interconnects, totaling approximately 186 miles of pipeline with diameters ranging from 6 to 30 inches; and new compression totaling over 400,000 horsepower at 8 new and 1 existing compressor stations.  Project facilities would be located in Texas, New Mexico, and Arizona. 

On March 26, 2026, the Applicants submitted this Project map to the docket. To view and download this map, please visit FERC's eLibrary and search Docket No. PF26-9-000. 

Pre-filing Environmental Review Process 

Pre-filing is a “pre-application” phase in the overall environmental review process for interstate natural gas or liquefied natural gas projects under FERC’s jurisdiction. The Pre-filing Process is designed to identify and address environmental aspects of the project before an official application is filed. The Pre-filing Process was established to encourage early involvement by stakeholders during the design and/or routing of an interstate natural gas project.

During the Pre-filing Process, members of the public will have multiple opportunities to get involved and express their views, concerns, and issues. Those opportunities include public comment periods, applicant-sponsored open houses, and scoping sessions hosted by FERC. These opportunities will be posted in FERC’s eLibrary in Docket No. PF26-9-000.

Public Participation Opportunities

Federal law requires FERC to seek out public comments and consider them during its review of a project. Public comments inform FERC’s reviews and serve to educate decision-makers about local concerns.

More Information and Staying Updated

You may learn more about the Project through FERC’s eLibrary. When searching for the Project, please enter Docket No. PF26-9-000 in the “Enter Docket Number” text box. FERC’s Office of Public Participation provides an educational video and demonstration on using eLibrary: WorkshOPP and Demonstration: FERC’s eLibrary. 

There is one docket associated with this Project:   

• The Pre-Filing Docket: Docket No. PF26-9-000

Stay Informed:

Follow OPP on its social media channels:  

• X  
• Facebook 
• LinkedIn 
• Instagram 
• Bluesky 

OPP regularly sends announcements about upcoming participation opportunities and meetings with interested stakeholders and organizations via its social media channels.  

You may also sign up for FERC’s eSubscription service. eSubscription notifies you via email about submittals and issuances on the project. Please visit www.ferc.gov/esubscription.

You are also encouraged to contact OPP staff to learn more about the Project and participation at FERC by email at [email protected] or phone at 202-502-6595. All media inquiries should be directed to [email protected].

Resources

Guides on Public Participation 

• Step-by-step guide on how to file a comment 
• Step-by-step guide on how to intervene 

Educational Videos 

• Learn to eFile, eComment, and eSubscribe 
• How to File an Intervention Using FERC’s Online System 
• Filing Comments Workshop and Demonstration
• Submitting Powerful Comments Workshop

Tips on Public Participation 

• How to Submit Effective Comments 
• Powerful Comments 
• Filing an Intervention

Informational Handouts 

• About FERC 
• About OPP 
• Natural Gas Pre-filing Open Houses: Public Participation and What to Expect
• Natural Gas Scoping Sessions: Public Participation and What to Expect

Office of Public Participation’s Outreach Corner

The Office of Public Participation (OPP) is authorized to support public participation in FERC proceedings pursuant to Section 319 of the Federal Power Act. OPP coordinates with and provides assistance to members of the public as to participation in, and understanding of, FERC proceedings. OPP provides outreach to community groups, community members, landowners and other interested parties potentially impacted by infrastructure projects. 

OPP’s outreach conducted for the Desert Southwest Expansion Project, FERC Docket No. PF26-9-000 included:

• OPP staff attended open houses across multiple locations, including Deming and Las Cruces in New Mexico; Safford, Wilcox, and Oracle in Arizona; and Pecos, Kermit, Mentone, El Paso, Dell City, and Van Horn in Texas. These events were held simultaneously in the various states to maximize engagement with the public.

How to Contact